Wrapper to allow span queries to participate in composite single-field span queries by lying about their search field. The span field masking query maps to Lucene’s SpanFieldMaskingQuery

This can be used to support queries like span-near or span-or across different fields, which is not ordinarily permitted.

Span field masking query is invaluable in conjunction with multi-fields when same content is indexed with multiple analyzers. For instance we could index a field with the standard analyzer which breaks text up into words, and again with the english analyzer which stems words into their root form.